Polypyrrole doped with fluoro-metal complexes: thermal stability and structural properties

Chemically produced polypyrrole powders doped with the fluoro-complexes fluoro-aluminates, fluoro-zirconates, fluoro-titanates and fluorides are synthesized and characterized by both XPS and four-probe conductivity measurements. The results show that the polypyrrole powders produced were doped with fluorides and with fluoro-metal complexes (Zr, Ti, Al) of different coordination numbers. Also, a significant incorporation of sulfates originating from the oxidant was determined. The relative concentration of the sulfates and of the respective fluoro-metal complexes is strongly affected by the size of these dopants and much less from their concentration in the solution. The aging process of these polymers is investigated. We have found that there are two main mechanisms, the oxidation of the polymeric chain by water and oxygen as well as the reaction of fluoride ions with low coordination fluoro-complexes to form stable complexes of higher coordination number. In the case of polypyrrole powder doped with fluorides, the mobility of these counter-ions leads to the formation of gaseous species. Polypyrrole powders doped with fluoro-zirconates and fluoro-titanates exhibit both good stability in contrast to those doped with fluoro-aluminates and fluorides.